Past Interactions Research Articles

Small-scale stellar haloes: detecting low surface brightness features in the outskirts of Milky Way dwarf satellites

ABSTRACT Dwarf galaxies are valuable laboratories for dynamical studies related to dark matter and galaxy evolution, yet it is currently unknown just how physically extended their stellar components are. Satellites orbiting the Galaxy’s potential may undergo tidal stripping by the host, or alternatively, may themselves have accreted smaller systems whose debris populates the dwarf’s own stellar halo. Evidence of these past interactions, if present, is best searched for in the outskirts of the satellite. However, foreground contamination dominates the signal at these large radial distances, making observation of stars in these regions difficult. In this work, we introduce an updated algorithm for application to Gaia data that identifies candidate member stars of dwarf galaxies, based on spatial, colour–magnitude and proper motion information, and which allows for an outer component to the stellar distribution. Our method shows excellent consistency with spectroscopically confirmed members from the literature despite having no requirement for radial velocity information. We apply the algorithm to all ∼60 Milky Way dwarf galaxy satellites, and we find nine dwarfs (Boötes 1, Boötes 3, Draco 2, Grus 2, Segue 1, Sculptor, Tucana 2, Tucana 3, and Ursa Minor) that exhibit evidence for a secondary, low-density outer profile. We identify many member stars which are located beyond 5 half-light radii (and in some cases, beyond 10). We argue these distant stars are likely tracers of dwarf stellar haloes or tidal streams, though ongoing spectroscopic follow-up will be required to determine the origin of these extended stellar populations.

Long-Read-Based Genome Assembly Reveals Numerous Endogenous Viral Elements in the Green Algal Bacterivore Cymbomonas tetramitiformis.

The marine tetraflagellate Cymbomonas tetramitiformis has drawn attention as an early diverging green alga that uses a phago-mixotrophic mode of nutrition (i.e., the ability to derive nourishment from both photosynthesis and bacterial prey). The Cymbomonas nuclear genome was sequenced previously, but due to the exclusive use of short-read (Illumina) data, the assembly suffered from missing a large proportion of the genome's repeat regions. For this study, we generated Oxford Nanopore long-read and additional short-read Illumina data and performed a hybrid assembly that significantly improved the total assembly size and contiguity. Numerous endogenous viral elements were identified in the repeat regions of the new assembly. These include the complete genome of a giant Algavirales virus along with many genomes of integrated Polinton-like viruses (PLVs) from two groups: Gezel-like PLVs and a novel group of prasinophyte-specific PLVs. The integrated ∼400 kb genome of the giant Algavirales virus is the first account of the association of the uncultured viral family AG_03 with green algae. The complete PLV genomes from C. tetramitiformis ranged between 15 and 25 kb in length and showed a diverse gene content. In addition, heliorhodopsin gene-containing repeat elements of putative mirusvirus origin were identified. These results illustrate past (and possibly ongoing) multiple alga-virus interactions that accompanied the genome evolution of C. tetramitiformis.

Offline reinforcement learning in high-dimensional stochastic environments

Offline reinforcement learning (RL) has emerged as a promising paradigm for real-world applications since it aims to train policies directly from datasets of past interactions with the environment. The past few years, algorithms have been introduced to learn from high-dimensional observational states in offline settings. The general idea of these methods is to encode the environment into a latent space and train policies on top of this smaller representation. In this paper, we extend this general method to stochastic environments (i.e., where the reward function is stochastic) and consider a risk measure instead of the classical expected return. First, we show that, under some assumptions, it is equivalent to minimizing a risk measure in the latent space and in the natural space. Based on this result, we present Latent Offline Distributional Actor-Critic (LODAC), an algorithm which is able to train policies in high-dimensional stochastic and offline settings to minimize a given risk measure. Empirically, we show that using LODAC to minimize Conditional Value-at-Risk (CVaR) outperforms previous methods in terms of CVaR and return on stochastic environments.

Mapping Strontium Isotope Geographical Variability as a Basis for Multi-regional Human Mobility: The Sybaris Region (S Italy) in the Early 1st Millennium BC

ABSTRACT Archaeological findings from the 8th c. BC settlement at Francavilla Marittima (CS) and its necropolis on the nearby Macchiabate plateau point to multi-regional interactions and the emergence of new identities in connection with the establishment of the Greek colony Sybaris. Strontium isotope analysis (87Sr/86Sr) is an efficient method to reconstruct human mobility and provides new insights into the Iron Age and Archaic period in the Calabria region. A successful interpretation of Sr isotope compositions in human tissues requires a baseline of the bioavailable strontium in the landscape of Francavilla Marittima and its surroundings. This study presents 87Sr/86Sr values of modern vegetation and water from North Calabria to establish the first finely resolved Sr isotope baseline map of this region. Sr isotope compositions vary between 0.7082 and 0.7127 and reflect the geological and lithological diversity of the study region. The regional 87Sr/86Sr variability exceeds the baseline of bioavailable 87Sr/86Sr at Francavilla Marittima and enables the integration of past regional interaction in data interpretation of the human remains. Several mapping and prediction methods were tested to produce surface models of the isotopic landscape, and the isotope group map is proposed as a suitable representation of the bioavailable Sr in the studied region.

Characterizing Social Connectedness and Associated Mental Health Symptoms among Sexual Minority Men Enrolled in a Substance Use Recovery Support Program

Background Sexual minority men (SMM; gay, bisexual, and other men who have sex with men) report higher rates of substance use compared to other populations. Social connectedness is a critical component for promoting and maintaining recovery from substance use disorders. However, the degree of social connectedness among SMM who report substance use is largely unknown. Objectives We examined substance use, social connectedness (past 30-d participation in formal recovery support, past 30-d interaction with supportive family/friends, relationship satisfaction, and types of support) and mental health among SMM at the time of their enrollment in a behavioral substance use program from September 2019 to October 2021. Results Of the107 SMM, 80% of the sample reported past 30-d illicit substance use, with methamphetamine representing the most commonly reported drug used (53%). Participants used a variety of social connections for support, including self-help groups (44% voluntary; 5% religious-affiliated; 20% other) and family/friends (81%). Importantly, 15% reported they had no one to turn to when having trouble and 36% were either dissatisfied or very dissatisfied with their relationships. Participants who endorsed significant depressive (58%) and anxiety (70%) symptoms were more likely to endorse relationship dissatisfaction than participants who did not endorse symptoms (p < 0.01). Conclusions One-third of SMM enrolled in a substance use recovery program expressed relationship dissatisfaction, particularly those struggling with depression or anxiety. Future research and programming should examine ways of leveraging existing social connectedness or forging new social supports to enhance mental health and substance use recovery for SMM using substances.

Contourite stratigraphic models linked to the light intermediate versus dense deep Mediterranean water flow regime variations (Alboran Sea, SW Mediterranean)

Several water masses are involved in the circulation of oceans, their bottom layers impacting on sedimentation through contourites. The majority of palaeoceanographic studies on regional contourites are performed for one water mass despite that their joint study would offer relevant clues to understand past ocean and climate interaction. This works presents for the first time a an analysis about the impact of the Light Intermediate Mediterranean (LMW) and Dense Deep Mediterranean (DMW) bottom currents on the sedimentation in the Alboran Sea (SW Mediterranean) and its paleoceanographic significance in response to climatic oscillations from the last glacial period to the Holocene. To do this, an integration of chronostratigraphical, sedimentological, and compositional data is carried out from contourites formed by those water masses. That integration enable us to define three distinct contourite stratigraphic models. (I) The contourite terrace model, characterized by coarse-grained contourites, which is an archive of the interplay between the high-energy Atlantic Water-LMW interface and glacioeustasy from the Younger Dryas (YD) to the Holocene. (II) The contourite drift models, which are archives of rapid ocean-climate coupled fluctuations since 29.5 kyr. They comprise coarse-grained contourites formed by a relatively fast LMW and fine-grained contourites formed by a relatively weak DMW, except for the Heinrich Stadials HS3 to HS1 and YD when coarse-grained contourites were deposited. (III) The contourite/turbidite mixed model represents another archive of DMW and glacioeustasy interplay from the end of the late Pleistocene to Holocene.That contourite stratigraphy allows us to infer for the first time the relative variability of the LMW versus DMW flow regimes, which records differences and similarities. The similarities indicate that the LMW and DMW fluctuations occur in parallel at millennial and centennial time scales. The differences refer to the overall higher velocity of LMW versus DMW; the magnitude changes in velocities that are lower for LMW and higher for DMW; the recognition of three short ventilation events (a, b, c) during HS1 and HS2 for only DMW; and the distinct LMW and DMW responses to the onset of glacial conditions and return to interglacial conditions during the HSs, YD and Holocene cold periods.The proposed contourite stratigraphic models can be applied for other areas in the Mediterranean margins to identify and correlate the LMW and DMW palaeoceanographic events throughout this sea. The findings suggest that the different water masses that make up the water column must be seriously considered to fully understand palaeoceanographic and palaeoclimatic studies based on contourites. This is because their distinct impact on sedimentation may provide new insights into their different palaeoceanographic responses to rapid climatic oscillations and their triggering mechanisms.

Human impact on vegetation at Lago di Vedana (Dolomites, Northern Italy) during the last seven centuries

Studying the legacies of past human-environment interactions is essential for understanding current landscape and biodiversity patterns. Human influences on past terrestrial and aquatic vegetation are reconstructed based on palynological analysis conducted on a sediment core from Lago di Vedana (Province of Belluno, Northern Italy). This study represents the first pollen record from the Dolomitic lowlands with varying anthropogenic influences throughout the last 700 years. The radiocarbon-dated pollen record begins ca. A.D. 1300 with semi-open forest and moderate human impact, possibly due to activities of the nearby hospice of San Gottardo. Human impact increased with the foundation of the Vedana Charterhouse in the immediate catchment of the lake in A.D. 1457. Activities of the monks involved extensive forest clearing, cultivation of Cannabis/Humulus and possibly hemp retting. In the 19th century the composition of cultivated species changed following the transformation of the Charterhouse into a farm. The 20th century is characterized by expansion of forest taxa and a distinct decline of human influences, probably due to a rural exodus and abandonment of agricultural activities. Vegetation development at Lago di Vedana is consistent with general trends in the Italian Alps and reveals local cultivation practices. The results illustrate the close intertwinement of climatic trends and local human influences, modulated by regional socio-cultural developments during the last millennium.

Ethnolinguistic and genetic diversity of fonio (Digitaria exilis) in Senegal

Societal Impact StatementFonio (Digitaria exilis—Kippist—Stapf) is a neglected cereal crop that plays a crucial role in the food and nutritional security of sub‐Saharan populations. Currently threatened with extinction in many countries, fonio, like other minor species, could help give insights into the history of African agriculture and provide clues to past social interactions. Highlighting and preserving genetic diversity that can be used to develop improved varieties improves food security. By recognizing the role of indigenous people and local communities (IPLCs) in agrobiodiversity creation and management, this study provides support for strengthening the rights of rural communities and promoting their food and seed sovereignty as outlined in the United Nations UNDROP Declaration.Summary Fonio (Digitaria exilis) is a neglected cereal crop that plays a crucial role in the food and nutritional security of sub‐Saharan populations. It is an excellent candidate to diversify agricultural and food systems beyond Africa because of its adaptability and hardiness. However, fonio is threatened with extinction and the factors that organize its genetic diversity remain unknown, despite the fact that this knowledge is necessary to define conservation strategies and uses to achieve sustainable agriculture. Here, we combined social anthropology and population genetics analysis of 158 fonio landraces, thereby generating insight into the genetic diversity, population structure and evolutionary history of fonio cultivation in Senegal. We noted a spatial structure of genetic diversity at two embedded levels, with the first corresponding to the genetic differentiation between ethnic groups and the second to the demographic history of the Mande and Atlantic Congo linguistic families. Selection and seed exchange practices have contributed to shaping fonio genetic diversity at the ethnic level, while the migration of Fulani people over the last 500 years has fragmented the Mandinka kingdom, hence leaving a fonio diversity imprint. Our study highlighted that social factors are pivotal in structuring diversity and should be taken into greater consideration in research and conservation projects to dovetail local and regional scales. It also showed that neglected species such as fonio—which are seldom used in breeding and dissemination programmes—are key markers of the history of African agriculture.

The AMIGA sample of isolated galaxies

Context. In the standard cosmological model of galaxy evolution, mergers and interactions play a fundamental role in shaping galaxies. Galaxies that are currently isolated are thus interesting because they allow us to distinguish between internal and external processes that affect the galactic structure. However, current observational limits may obscure crucial information in the low-mass or low-brightness regime. Aims. We use optical imaging of a subsample of the AMIGA catalogue of isolated galaxies to explore the impact of different factors on the structure of these galaxies. In particular, we study the type of disc break as a function of the degree of isolation and the presence of interaction indicators such as tidal streams or plumes, which are only detectable in the ultra-low surface brightness regime. Methods. We present ultra-deep optical imaging in the r band of a sample of 25 low-redshift (z &lt; 0.035) isolated galaxies. Through careful data processing and analysis techniques, the nominal surface brightness limits achieved are comparable to those to be obtained on the ten-year LSST coadds (μr,lim ≳ 29.5 mag arcsec−2 [3σ; 10″ × 10″]). We place special emphasis on preserving the low surface brightness features throughout the processing. Results. The extreme depth of our imaging allows us to study the interaction signatures of 20 galaxies since Galactic cirrus is a strong limiting factor in the characterisation of interactions for the remaining 5 of them. We detect previously unreported interaction features in 8 (40% ± 14%) galaxies in our sample. We identify 9 galaxies (36% ± 10%) with an exponential disc (Type I), 14 galaxies (56% ± 10%) with a down-bending (Type II) profile, and only 2 galaxies (8% ± 5%) with up-bending (Type III) profiles. Isolated galaxies have considerably more purely exponential discs and fewer up-bending surface brightness profiles than field or cluster galaxies. We find clear minor merger activity in some of the galaxies with single exponential or down-bending profiles, and both of the galaxies with up-bending profiles show signatures of a past interaction. Conclusions. We show the importance of ultra-deep optical imaging in revealing faint external features in galaxies that indicate a probable history of interaction. We confirm that up-bending profiles are likely produced by major mergers, while down-bending profiles are probably formed by a threshold in star formation. Unperturbed galaxies that slowly evolve with a low star formation rate could induce the high rate of Type I discs in isolated galaxies.

A Multi-Robot-Based Architecture and a Trust Model for Intelligent Fault Management and Control Systems

One of the most important challenges in robotics is the development of a Multi-Robot-based control system in which the robot can make intelligent decisions in a changing environment. This paper proposes a robot-based control approach for dynamically managing robots in such a widely distributed production system. A Multi-Robot-based control system architecture is presented, and its main features are described. Such architecture facilitates the reconfiguration (either self-reconfiguration ensured by the robot itself or distributed reconfiguration executed by the Multi-Robot-based system). The distributed reconfiguration is facilitated through building a trust model that is based on learning from past interactions between intelligent robots. The Multi-Robot-based control system architecture also addresses other specific requirements for production systems, including fault flexibility. Any out-of-control fault occurring in a production system results in the loss of production time, resources, and money. In these cases, robot trust is critical for successful job completion, especially when the work can only be accomplished by sharing knowledge and resources among robots. This work introduces research on the construction of trust estimation models that experimentally calculate and evaluate the trustworthiness of robots in a Multi-Robot system where the robot can choose to cooperate and collaborate exclusively with other trustworthy robots. We compare our proposed trust model with other models described in the literature in terms of performance based on four criteria, which are time steps analysis, RMSD evaluation, interaction analysis, and variation of total feedback. The contribution of the paper can be summarized as follows: (i) the Multi-Robot-based Control Architecture; (ii) how the control robot handles faults; and (iii) the trust model.

An Example of Geographic Network Analysis: The Case Study of the Fortore Valley (Molise and Apulia, Italy)

Abstract Today, the Fortore River is the geographic and administrative boundary between the regions of Molise and Apulia. In the past decade, scholars have debated Fortore’s role during the pre-Roman and Roman periods, specifically focusing on how this physical boundary may have influenced the interaction and connectivity between Samnium (modern-day Molise) and Daunia (modern-day northern Apulia). Both ancient literary sources and archaeological finds indicate the situation is complicated, and it is challenging to locate the geographical and cultural borders, especially in the pre-Roman period. This article suggests a model to understand the past interaction between the two modern-day areas of Macchia Valfortore (Molise) and Carlantino (Apulia). These sites were in the proximity of the Fortore River, and an investigation of material culture in both locations revealed a complex and diverse society between the sixth century BC and the first century BC. The small-scale spatial networks constructed help to explain the interchange dynamics between the two districts and, furthermore, how each of them related to the ancient road system. The case study demonstrates, moreover, how a not conventional archaeological approach may also highlight the prominence of river connections for economic and social development.

PM2.5 exposure promotes asthma in aged Brown-Norway rats: Implication of multiomics analysis

Children are disproportionately represented among those who suffer asthma, which is a kind of chronic airway inflammation. Asthma symptoms might worsen when exposed to the air pollutant particulate matter 2.5 (PM2.5). However, it is becoming more prevalent among older adults, with more asthma-related deaths occurring in this pollution than in any other age group, and symptoms caused by asthma can reduce the quality of life of the elderly, whose asthma is underdiagnosed due to physiological factors. Therefore, in an effort to discover a therapy for older asthma during exposure to air pollution, we sought to ascertain the effects of pre-exposure (PA) and persistent exposure (PAP) to PM2.5 in aged asthma rats. In this study, we exposed aged rats to PM2.5 at different times (PA and PAP) and established an ovalbumin-mediated allergic asthma model. The basic process of elderly asthma caused by PM2.5 exposure was investigated by lung function detection, enzyme-linked immunosorbent assay (ELISA), histopathology, cytology, cytokine microarray, untargeted metabolomics, and gut microbiota analysis. Our findings demonstrated that in the PA and PAP groups, exposure to PM2.5 reduced lung function and exacerbated lung tissue damage, with varying degrees of effect on immunoglobulin levels, the findings of a cytological analysis, cytokines, and chemokines. The PA and PAP rats had higher amounts of polycyclic aromatic hydrocarbons (PAHs), such as naphthalene, 2-methylNaphthalene, 1-methylNaphthalene and flourene. Moreover, exposure to PM2.5 at different times showed different effects on plasma metabolism and gut microbiota. Bioinformatics analysis showed a strong correlation between PAHs, cytokines, and gut microbiota, and PAHs may cause metabolic disorders through the gut microbiota. These findings point to a possible mechanism for the development of asthma in older people exposure to PM2.5 that may be related to past interactions between PAHs, cytokines, gut microbiota, and plasma metabolites.

The Roles of Cultural Capital in Teacher-Student Interactions in China: A Qualitative Study of Students in Higher Vocational Colleges.

The theory of cultural capital has long been applied to explain academic achievement. This qualitative study investigated first-year students in higher vocational colleges and, taking this low cultural capital group as an example, explored how cultural capital has affected their past teacher-student interactions. Participants described their experience of interacting with their teachers. We found that these students primarily experienced authoritative and laissez-faire teacher-student interactions. Students' embodied and institutionalized cultural capital profoundly affected different aspects of the teacher-student interaction. In modern China, vocational and academic education are of the same status, so teachers should modify their evaluations based solely on academic achievement. When interacting with students, teachers should be more understanding and interact in a more student-centred way. Teacher training programmes should also be reformed, and training for teachers in general and vocational schools should be distinguished.

A Multi-Temporal Analysis of Archaeological Site Destruction using Landsat Satellite Data and Machine Learning, Moche Valley, Peru

The destruction of archaeological sites and the loss of archaeological landscapes remains a global concern as populations and urban areas continue to expand. Archaeological sites are not only significant to local communities, national identities, and modern tourist economies but also provide critical knowledge of past sociocultural interactions, settlement patterns, human-environment relationships, and risk mitigation strategies. While archaeological landscapes and site destruction have remained outside of traditional land use land cover change (LULCC) studies, they are a form of urban and agricultural land use. By conceptualizing archaeological site destruction within land change science, this study provides an innovative approach for assessing “what's left” of historically surveyed archaeological landscapes. Using a Random Forest algorithm and Landsat satellite data, this study quantifies archaeological site destruction attributed to LULCC in Peru's lower Moche Valley between 1985 and 2020. More than 400 archaeological sites previously recorded during the Chan Chan-Moche Valley Project (CCMVP, 1969–1974) are analyzed. Results indicate that less than a quarter of the original CCMVP sites remain on the landscape. The primary drivers of LULCC in the lower Moche Valley include population growth, migration, and government policies, while secondary drivers include heritage values. Positioning archaeological survey data within land change science and integrating machine learning techniques can benefit historic survey reassessments globally and provides significant knowledge of archaeological site destruction and the socioeconomic conditions that underly dynamic landscape changes.

Extreme mass ratios and fast rotation in three massive binaries

ABSTRACT The origin of rapid rotation in massive stars remains debated, although binary interactions are now often advocated as a cause. However, the broad and shallow lines in the spectra of fast rotators make direct detection of binarity difficult. In this paper, we report on the discovery and analysis of multiplicity for three fast-rotating massive stars: HD 25631 (B3V), HD 191495 (B0V), and HD 46485 (O7V). They display strikingly similar TESS light curves, with two narrow eclipses superimposed on a sinusoidal variation due to reflection effects. We complement these photometric data by spectroscopy from various instruments (X-Shooter, Espadons, FUSE...), to further constrain the nature of these systems. The detailed analyses of these data demonstrates that the companions of the massive OB stars have low masses (∼1 M⊙) with rather large radii (2–4 R⊙) and low temperatures (&amp;lt;15 kK). These companions display no UV signature, which would exclude a hot subdwarf nature, but disentangling of the large set of X-Shooter spectra of HD 25631 revealed the typical signature of chromospheric activity in the companion’s spectrum. In addition, despite the short orbital periods (P = 3−7 d), the fast-rotating OB-stars still display non-synchronized rotation and all systems appear young (&amp;lt;20 Myr). This suggests that, as in a few other cases, these massive stars are paired in those systems with non-degenerate, low-mass PMS companions, implying that fast rotation would not be a consequence of a past binary interactions in their case.

Task Scheduling Mechanism Based on Reinforcement Learning in Cloud Computing

The explosive growth of users and applications in IoT environments has promoted the development of cloud computing. In the cloud computing environment, task scheduling plays a crucial role in optimizing resource utilization and improving overall performance. However, effective task scheduling remains a key challenge. Traditional task scheduling algorithms often rely on static heuristics or manual configuration, limiting their adaptability and efficiency. To overcome these limitations, there is increasing interest in applying reinforcement learning techniques for dynamic and intelligent task scheduling in cloud computing. How can reinforcement learning be applied to task scheduling in cloud computing? What are the benefits of using reinforcement learning-based methods compared to traditional scheduling mechanisms? How does reinforcement learning optimize resource allocation and improve overall efficiency? Addressing these questions, in this paper, we propose a Q-learning-based Multi-Task Scheduling Framework (QMTSF). This framework consists of two stages: First, tasks are dynamically allocated to suitable servers in the cloud environment based on the type of servers. Second, an improved Q-learning algorithm called UCB-based Q-Reinforcement Learning (UQRL) is used on each server to assign tasks to a Virtual Machine (VM). The agent makes intelligent decisions based on past experiences and interactions with the environment. In addition, the agent learns from rewards and punishments to formulate the optimal task allocation strategy and schedule tasks on different VMs. The goal is to minimize the total makespan and average processing time of tasks while ensuring task deadlines. We conducted simulation experiments to evaluate the performance of the proposed mechanism compared to traditional scheduling methods such as Particle Swarm Optimization (PSO), random, and Round-Robin (RR). The experimental results demonstrate that the proposed QMTSF scheduling framework outperforms other scheduling mechanisms in terms of the makespan and average task processing time.

A realist analysis of civilized tourism in China: a cultural structural perspective

ABSTRACT In the discourse of value-laden tourism research, knowledge about the mechanisms that manifest civilized tourism is limited. This paper uses empirical research as a basis from which to explore the generative powers of civilized tourism at the structural level of society. It identifies the structural properties of civilized tourism and five situational logics. Civilized tourism is related to civility, China’s Dream, and social etiquette. These other ideas provide a condition for civilized tourism to exist. All the situational logics function to co-determine the nature of civilized tourism in the cultural system. Based on the findings, it concludes that the call for civilized tourism in China provides a condition for the formation of ethicality in tourism, which is not reducible to tourism stakeholders. The formation of ethicality is conditioned by the product of past socio-cultural interactions whilst engineered by the protective and corrective situational logics of the idealizations taking place in the present time.

A description and sensitivity analysis of the ArchMatNet agent-based model.

Archaeologists cannot observe face-to-face interactions in the past, yet methods derived from the analyses of social networks are often used to make inferences about patterns of past social interactions using material cultural remains as a proxy. We created the ArchMatNet agent-based model to explore the relationship between networks built from archaeological material and the past social networks that generated them. It was designed as an abstract model representing a wide variety of social systems and their dynamics: from hunter-gatherer groups to small-scale horticulturalists. The model is highly flexible, allowing agents to engage in a variety of activities (e.g., group hunting, visiting, trading, cultural transmission, migration, seasonal aggregations, etc.), and includes several parameters that can be adjusted to represent the social, demographic and historical dynamics of interest. This article examines how sensitive the model is to changes in these various parameters, primarily by relying on the one-factor-at-a-time (OFAT) approach to sensitivity analysis. Our purpose is for this sensitivity analyses to serve as a guide for users of the model containing information on how the model works, the types of agents and variables included, how parameters interact with one another, the model outputs, and how to make informed choices on parameter values.

Forecasting User Interests Through Topic Tag Predictions in Online Health Communities.

The increasing reliance on online communities for healthcare information by patients and caregivers has led to the increase in the spread of misinformation, or subjective, anecdotal and inaccurate or non-specific recommendations, which, if acted on, could cause serious harm to the patients. Hence, there is an urgent need to connect users with accurate and tailored health information in a timely manner to prevent such harm. This article proposes an innovative approach to suggesting reliable information to participants in online communities as they move through different stages in their disease or treatment. We hypothesize that patients with similar histories of disease progression or course of treatment would have similar information needs at comparable stages. Specifically, we pose the problem of predicting topic tags or keywords that describe the future information needs of users based on their profiles, traces of their online interactions within the community (past posts, replies) and the profiles and traces of online interactions of other users with similar profiles and similar traces of past interaction with the target users. The result is a variant of the collaborative information filtering or recommendation system tailored to the needs of users of online health communities. We report results of our experiments on two unique datasets from two different social media platforms which demonstrates the superiority of the proposed approach over the state of the art baselines with respect to accurate and timely prediction of topic tags (and hence information sources of interest).

Sandinista Revolution: a Postcolonial Approach to USA Interventionism

"The Sandinista Revolution was a watershed moment in Nicaraguan history that forever altered the course of the country's history. First, it dismantled the Somoza family's dynasty, which had ruled for 43 years, not all of them consecutively, and established a political system dependent on their despotic regime. Second, and more significantly for international relations, the Sadinistas' denunciation of the neo-colonialism committed by the leader of the western democracies was a direct attack on US interventionism in Central America. Unfortunately, it was also the point at which the FSLN established its roots in Nicaraguan society and transitioned from a socialist movement to an authoritarian regime under Daniel Ortega. In order to analyse these evolutions of events I propose a postcolonial theoretical approach. The fact that postcolonialism is a relatively new addition to the international relations theory that first appeared in literature is one of the primary justifications for why this theoretical approach relies on information from native authors. This theory mainly focuses on the former colonies and criticises how the colonial past and present interactions with the former colonists have an impact on how those colonies have developed. I will examine the key ideas of these approaches in the international arena with respect to the particular case of the Sandinista Revolution in Nicaragua. Keywords: Latin America, postcolonialism, Sandinista Revolution, discourse analysis, United States of America."